HR: 1340h
AN: A43A-0035    [Abstracts]
TI: The Role of Tropospheric Temperature in the ENSO-driven Surface Temperature Variability over the Remote Tropics
AU: * Chiang, J C
EM: jchiang@atmos.berkeley.edu
AF: Dept of Geography, University of California, 547 McCone Hall, Berkeley, CA 94720-4740 United States
AU: Lintner, B R
EM: ben@atmos.berkeley.edu
AF: Dept of Geography, University of California, 547 McCone Hall, Berkeley, CA 94720-4740 United States
AU: Sobel, A H
EM: ahs129@columbia.edu
AF: Dept. of Applied Physics and Applied Mathematics, Columbia University, SW Mudd 217 500 W 120th St, New York, NY 10027 United States
AB: Previous observational and modeling studies have shown the importance of wind speed and the shortwave influence of cloud cover in mediating the El Ni¤o warming overthe remote tropical oceans via the `atmospheric bridge'. We argue - based on simulations with a single column model and with an atmospheric GCM coupled to a thermodynamic slab ocean model - that atmospheric boundary layer humidity effects, and also the influence of net LW, can also be significant influences. The relative strengths of each surface flux influence differ from region to region, indicating the complicating influence of regional climate processes. However, we argue thattropospheric temperature plays a central role in the El Nino-related remote surface temperature warming by i) communicating the ENSO influence to the remote tropics; and ii) setting the equilibrium surface temperature response over moist convective regions, through the convective quasi-equilibrium constraint linking planetary boundary layer moist static energy to the free tropospheric temperature. This constraint offers a simple explanation why all remote moist convective regions (over ocean and land) warm during and after the El Ni¤o peak, despite the region-dependent nature of the surface flux response.
DE: 3339 Ocean/atmosphere interactions (0312, 4504)
DE: 4215 Climate and interannual variability (3309)
DE: 4522 El Ni¤o
DE: 1854 Precipitation (3354)
DE: 1620 Climate dynamics (3309)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting